The UPS does not work from the network. Uninterruptible power supply failure. Such a useful and necessary UPS
Uninterruptible power supplies, like any other equipment, need timely maintenance, the absence of which can lead to the fact that the UPS will not start. This is possible for a variety of reasons. There is a set of typical malfunctions that can lead to the UPS not turning on, however, it is worth remembering that each UPS device may have its own characteristics, which can make its own adjustments to the UPS diagnostics and repair process.
Since the UPS is the most important part of the power system, failure of the UPS exposes the equipment to some degree of risk. The easiest way to troubleshoot the problem is to study the instructions. With a high degree of probability, there you will find a description of the problems that may appear during the operation of a specific model of an uninterruptible power supply. Most of the instructions contain at least a little information on how to troubleshoot a minor problem.
To avoid problems, it is advisable to use the software that comes with the UPS. With its help, you can monitor the state of the system and take the necessary measures in a timely manner.
Functional check
How to check the UPS for performance? To do this, you need to turn off the electricity and monitor the operating time of the load. If the operating time is short, then the malfunction is more likely to be caused by high battery wear... In this case, repairing an uninterruptible power supply for a computer will be a banal replacement. It is important to remember that old batteries should not be thrown away due to their high environmental impact - old batteries must be taken for recycling.
If the UPS beeps at startup, then this may be a signal that a overload... It can also signal that the battery failed the test, which is provided by the system. You can understand the reason for the unpleasant squeak using the indicators on the front panel or using the software.
Eaton 9PX UPS Control Panel
Why is the UPS not running on battery? This problem can be caused by defective charger, as a result of which the battery is not able to provide the declared battery life. You can check the charging by measuring the voltage at the terminals without disconnecting from the network. It should be 13-14V for a UPS with one battery and 26-28V for a series connected battery.
If the uninterruptible power supply for the computer does not work, then first you need to check the condition of the battery. In general, their service life is 4-5 years maximum. If your UPS is more than 5 years old, then most likely the whole problem is in the battery. The battery condition can be determined by the voltage level. If it is higher than 12.4 V, then everything is in order, and if it is less than 12 V, then it's time to say goodbye to it.
You can also check the battery using an ordinary 100 W light bulb. To do this, you need to connect the light bulb to the battery and see how long the battery charge will last. Typical batteries used in uninterruptible power supplies are lead-acid with a capacity of 7 Ah. A new battery of this type provides about 20 minutes of operation for a 100 W bulb. As a result, if the battery shows a time that is less than 70% of the normal, then it must be replaced.
If the battery is working properly, then the reasons for the malfunction may lie in incorrect battery connection... Also, the reason may be incorrect execution of the UPS program, this indicates that the device needs to be calibrated. Otherwise, the reasons may lie in UPS component malfunctions, which you cannot install on your own.
UPS does not turn on
Situations are not uncommon when an uninterruptible power supply simply does not turn on. What to do in this case? In low-power uninterruptible power supplies, as a rule, the control board is powered from the battery, in view of this, the uninterruptible power supply does not turn on due to low charge... In such a situation, you should try to charge the battery. Some devices can charge under these conditions, so simply plug the UPS into the mains and wait a while. Alternatively, you can remove the battery and charge it using a suitable charger.
If you have just purchased the device, but it does not turn on, then you need to check if the battery is connected. According to the transportation rules, such devices must be transported with the battery disconnected. Another reason that the UPS does not start may be etcdepressed power button... Possible cable breaks caused by a short circuit.
Also, the reason that the uninterruptible power supply does not work can be overload... It is quite simple to check this - you need to turn off the entire load. If at the same time the UPS will operate, then it is necessary to identify the equipment that is causing the overload. This can be done by connecting the load in series to the UPS. After that, such a load must be excluded. If the UPS does not turn on even without load, then it is necessary to submit the device for diagnostics to c. Replacing the battery yourself may not solve the problem, so it just makes no sense to buy a second battery.
Maintaining powerful UPSs can be dangerous. It is caused by the presence of high currents and voltages, which, when short-circuited, can damage the equipment and cause burns. For this reason, it is worth observing all precautions, and even better, contact a specialized center.
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In this article, I will share with you a method to diagnose and troubleshoot an uninterruptible power supply (UPS) failure. So and why the uninterruptible power supply may not turn on or not work from the network? one of the first reasons, a fuse has blown, a transformer or a control board may have failed, but in our case it is a little different, but at the same time a very elementary problem ...
Let's understand in more detail ...
Do-it-yourself uninterruptible power supply repair
At the very beginning, before disassembling, we need to check if the fuse is working, usually it is located on the back of the UPS.
We remove it and check it with a multimeter in the dial mode.
In this case, the fuse is good.
We proceed to disassembling the uninterruptible power supply (UPS) itself
I want to note that the method of disassembly may be different from your UPS model, but should not cause you any special difficulties in disassembly.
Unscrew 4 screws and remove the lower part of the IPB case.
After disassembling, carefully inspect the board for external damage to components. In our case, no damage was found.
The first step is to check the storage battery (AKB). Let's measure its voltage with a multimeter.
In our case, the battery is discharged to 2 volts, which is naturally not good and is a deep enough discharge.
Let's check the battery for charge-discharge by connecting it to the laboratory power supply unit for recharging in order to exclude the possibility of its breakdown.
As it turned out, the battery refused to take charge from the laboratory power supply, which means that there is a break somewhere and, accordingly, our battery is not working properly.
Let's take another battery for testing. In my case, it has a slightly higher capacity. Accordingly, the uninterruptible power supply should keep the charge longer and fits perfectly into the case from the UPS!
We connect the terminals - we will start for the test without assembling the case. Launched.
We measure its voltage: - 12.4 volts.
To make sure that the battery is charging, within a few seconds measure the voltage at the battery terminals when the UPS is connected to the network. The voltage should rise gradually.
12.9 volts tells us that the battery is charging, the uninterruptible power supply is operational, it can be assembled and put into operation.
Failure of a battery or a loss of its energy capacity is one of the most common failures among all types of UPS. So do not rush to throw them away.
The complete lack of information about such common devices as uninterruptible power supplies is surprising. We are breaking through the information blockade and are starting to publish materials on their construction and repair. From the article you will get a general idea of the existing types of UPS and a more detailed, at the level of a schematic diagram, about the most common Smart-UPS models.
The reliability of computers is largely determined by the quality of the electrical network. Power interruptions, such as surges, surges, sags, and power outages, can result in keyboard locks, data loss, system board damage, and more. Uninterruptible power supplies (UPS) are used to protect high-value computers from mains-related troubles. The UPS eliminates problems associated with poor quality power or temporary lack of power, but is not a long-term alternative power source like a generator.
According to the expert-analytical center "SK PRESS", in 2000 the volume of UPS sales in the Russian market amounted to 582 thousand units. If we compare these estimates with data on sales of computers (1.78 million pieces), it turns out that in 2000, every third computer purchased is equipped with an individual UPS.
The overwhelming part of the Russian UPS market is occupied by products of six companies: APC, Chloride, Invensys, IMV, Liebert, Powercom. APC products have been maintaining the leading position in the Russian UPS market for many years.
UPSs are divided into three main classes: Off-line (or stand-by), Line-interactive and On-line. These devices have various designs and characteristics.
Rice. 1. Block diagram of an off-line UPS
A block diagram of an Off-line UPS is shown in Fig. 1. During normal operation, the load is supplied by the filtered mains voltage. EMI / RFI Noise filters on metal oxide varistors are used to suppress EMI and RFI in the input circuits. If the input voltage falls below or above the set value or disappears altogether, the inverter turns on, which is normally off. By converting the DC voltage of the batteries into AC, the inverter supplies the load from the batteries. The shape of its output voltage is rectangular pulses of positive and negative polarity with an amplitude of 300 V and a frequency of 50 Hz. Off-line UPSs operate uneconomically in power grids with frequent and significant voltage deviations from the nominal value, since frequent switching to battery operation reduces the service life of the latter. The power of the Back-UPS Off-line UPS models produced by APC is in the range of 250 ... 1250 VA, and the Back-UPS Pro models are in the range of 2S0 ... 1400 VA.
Rice. 2. Block diagram of a Line-interactive UPS
A block diagram of a Line-interactive UPS is shown in Fig. 2. Just like the Off-line UPS, they retransmit the AC mains voltage to the load, while absorbing relatively small voltage surges and smoothing out noise. The input circuits use an EMI / RFI Noise filter on metal oxide varistors to suppress EMI and RFI. If an emergency occurs in the mains, then the UPS synchronously, without loss of the oscillation phase, turns on the inverter to supply the load from the batteries, while the sinusoidal shape of the output voltage is achieved by filtering the PWM oscillation. The circuit uses a special inverter to recharge the battery, which also operates during line voltage surges. The range of operation without battery connection is expanded due to the use of an autotransformer with a switched winding in the input circuits of the UPS. Transfer to battery power occurs when utility voltage is out of range. The capacity of the Line-interactive class UPSs of the Smart-UPS model manufactured by ARS is 250 ... 5000 VA.
Rice. 3. Block diagram of the UPS class On-line
The block diagram of the UPS of the On-line class is shown in Fig. 3. These UPSs convert the AC input voltage to DC, which is then converted back to stable AC by means of a PWM inverter. Since the load is always supplied by the inverter, there is no need to switch from the mains to the inverter, and the transfer time is zero. Due to the inertial DC link, which is the battery, the load is isolated from mains anomalies and a very stable output voltage is formed. Even with large deviations in the input voltage, the UPS continues to supply the load with pure sinusoidal voltage with a deviation of no more than + 5% of the user-set nominal value. APC On-line UPSs have the following output powers: Matrix UPS models - 3000 and 5000 VA, Symmetra Power Array models - 8000, 12000 and 16000 VA.
The Back-UPS models do not use a microprocessor, while the Back-UPS Pro, Smart-UPS, Smart / VS, Matrix, and Symmetna use a microprocessor.
The most widely used devices are: Back-UPS, Back-UPS pro, Smart-UPS, Smart-UPS / VS.
Devices such as Matrix and Symmetna are used primarily for banking systems.
In this article, we will consider the design and diagram of Smart-UPS 450VA ... 700VA models used to power personal computers (PCs) and servers. Their technical characteristics are given in table. one.
Table 1. Specifications for APC Smart-UPS models
| Model | 450VA | 620VA | 700VA | 1400VA |
|---|---|---|---|---|
| Allowable input voltage, V | 0...320 | |||
| Input voltage for mains operation *, V | 165...283 | |||
| Output voltage *, V | 208...253 | |||
| Input circuit overload protection | Resettable circuit breaker | |||
| Frequency range for mains operation, Hz | 47...63 | |||
| Time of switching to battery power, ms | 4 | |||
| Maximum power in load, VA (W) | 450(280) | 620(390) | 700(450) | 1400(950) |
| Output voltage during battery operation, V | 230 | |||
| Frequency when operating on battery, Hz | 50 ± 0.1 | |||
| Signal waveform when operating on battery power | Sinusoid | |||
| Output circuit overload protection | Overload and short-circuit protection, overload latching shutdown | |||
| Battery Type | Lead sealed, maintenance-free | |||
| Number of batteries x voltage, V, | 2 x 12 | 2 x 6 | 2 x 12 | 2 x 12 |
| Battery capacity, Ah | 4,5 | 10 | 7 | 17 |
| Battery life, years | 3...5 | |||
| Full charge time, h | 2...5 | |||
| UPS dimensions (height x width x length), cm | 16.8x11.9x36.8 | 15,8x13,7x35,8 | 21.6x17x43.9 | |
| Net weight (gross), kg | 7,30(9,12) | 10,53(12,34) | 13,1(14,5) | 24,1(26,1) |
* User adjustable using PowerChute software.
UPS Smart-UPS 450VA ... 700VA and Smart-UPS 1000VA ... 1400VA have the same electrical circuit and differ in battery capacity, the number of output transistors in the inverter, the power of the power transformer and dimensions.
Consider the parameters that characterize the quality of electricity, as well as the terminology and designations.
Power problems can be expressed as:
In Russia, voltage dips, power outages and surges both up and down account for approximately 95% of deviations from the norm, the rest is noise, impulse noise (needles), high-frequency surges.
Volt-Amperes (VA, VA) and Watts (W, W) are used as power units. They differ in power factor PF (Power Factor):
The power factor for computer technology is 0.6 ... 0.7. The number in the model designation of the APC UPS means the maximum power in VA. For example, the Smart-UPS 600VA model has a power of 400W, and the 900VA model has 630W.
The block diagram of the Smart-UPS and Smart-UPS / VS models is shown in Fig. 4. Mains voltage is applied to the EM / RFI input filter to suppress mains noise. At rated mains voltage, relays RY5, RY4, RY3 (pins 1, 3), RY2 (pins 1, 3), RY1 are switched on, and the input voltage is passed to the load. Relays RY3 and RY2 are used for the BOOST / TRIM output voltage trim mode. For example, if the mains voltage increased and went beyond the permissible limit, relays RY3 and RY2 connect an additional winding W1 in series with the main W2. An autotransformer with a transformation ratio is formed
K = W2 / (W2 + W1)
less than one and the output voltage drops. In the event of a decrease in the mains voltage, the additional winding W1 is reversed by the relay contacts RY3 and RY2. Transformation ratio
K = W2 / (W2 - W1)
becomes greater than one, and the output voltage rises. The adjustment range is ± 12%, the hysteresis value is selected by the Power Chute software.
In the event of a voltage failure at the input, relays RY2 ... RY5 are turned off, a powerful PWM inverter powered by a battery turns on, and a sinusoidal voltage of 230 V, 50 Hz is supplied to the load.
The multi-link filter for suppression of mains noise consists of varistors MV1, MV3, MV4, choke L1, capacitors C14 ... C16 (Fig. 5). The CT1 transformer analyzes the high-frequency components of the mains voltage. The CT2 transformer is a load current sensor. The signals from these sensors, as well as the RTH1 temperature sensor, are fed to the analog-to-digital converter IC10 (ADC0838) (Fig. 6).
Transformer T1 is an input voltage sensor. The command to turn on the device (AC-OK) is sent from the two-level comparator IC7 to the base of Q6. Transformer T2 - output voltage sensor for Smart TRIM / BOOST mode. From pins 23 and 24 of IC1 2 (Fig. 6), the BOOST and TRIM signals are fed to the bases of transistors Q43 and Q49 to switch relays RY3 and RY2, respectively.
The phase synchronization signal (PHAS-REF) from pin 5 of transformer T1 goes to the base of transistor Q41 and from its collector to pin 14 of IC12 (Figure 6).
The Smart-UPS model uses an IC12 microprocessor (S87C654), which:
The EEPROM IC13 stores the factory settings, as well as the calibrated settings for the signal levels of frequency, output voltage, transition limits, battery charging voltage.
Digital-to-analog converter IC15 (DAC-08CN) generates a sinusoidal reference signal at pin 2, which is used as a reference for IC17 (APC2010).
The PWM signal is generated by IC14 (APC2020) in conjunction with IC17. Powerful field-effect transistors Q9 ... Q14, Q19 ... Q24 form a bridge inverter. During the positive half-wave of the PWM signal, Q12 ... Q14 and Q22 ... Q24 are open, and Q19 ... Q21 and Q9 ... Q11 are closed. During the negative half-wave, Q19 ... Q21 and Q9 ... Q11 are open, and Q12 ... Q14 and Q22 ... Q24 are closed. Transistors Q27 ... Q30, Q32, Q33, Q35, Q36 form push-pull drivers that generate control signals for powerful field-effect transistors with a large input capacitance. The load of the inverter is the transformer winding, it is connected by wires W5 (yellow) and W6 (black). A sinusoidal voltage of 230 V, 50 Hz is generated on the secondary winding of the transformer to power the connected equipment.
Inverter reverse operation is used to charge the battery with a ripple current during normal UPS operation.
The UPS has a built-in SNMP slot that allows you to connect additional cards to expand the UPS's capabilities:
The UPS has several voltages required for the normal operation of the device: 24 V, 12 V, 5 V and -8 V. To check them, you can use table. 2. Measure the resistance from the terminals of the microcircuits to the common wire with the UPS turned off and the discharged capacitor C22. Typical malfunctions of UPS Smart-Ups 450VA ... 700VA and methods of their elimination are shown in table. 3.
Table 3. Typical UPS faults Smart-Ups 450VA ... 700VA
| Brief description of the defect | Possible reason | Troubleshooting method |
|---|---|---|
| UPS does not turn on | Batteries not connected | Connect batteries |
| Bad or defective battery, low capacity | Replace battery. The capacity of the charged battery can be checked with the high beam lamp from the car (12V, 150W) | |
| Powerful field-effect transistors of the inverter are pierced | In this case, there is no voltage at the terminals of the battery connected to the UPS board. Check with an ohmmeter and replace transistors. Check the resistors in their gate circuits. Replace IC16 | |
| Broken flexible cable connecting the display | This fault can be caused by shorting the flex cable leads in the UPS chassis. Replace the flex cable connecting the display to the main board of the UPS. Check if fuse F3 and transistor Q5 are working | |
| The power button is pressed | Replace SW2 button | |
| UPS turns on on battery power only | Fuse F3 blown | Replace F3. Check the health of transistors Q5 and Q6 |
| UPS will not start. Battery replacement indicator is on | If the battery is good, the UPS is not running the program correctly. | Calibrate the battery voltage using the proprietary program from APC |
| UPS does not come on line | Mains cable cut or connection broken | Connect the network cable. Check the condition of the automatic plug with an ohmmeter. Check the hot-neutral cord connection. |
| Cold soldering of board elements | Check the health and quality of the rations of elements L1, L2 and especially T1 | |
| Defective varistors | Check or replace varistors MV1 ... MV4 | |
| Load shedding occurs when the UPS is turned on. | Defective voltage sensor T1 | Replace T1. Check the health of the elements: D18 ... D20, C63 and C10 |
| Display indicators are flashing | The capacity of the capacitor C17 has decreased | Replace capacitor C17 |
| Capacitor leakage is likely | Replace C44 or C52 | |
| Defective relay contacts or board elements | Replace relay. Replace IC3 and D20. It is better to replace diode D20 with 1N4937 | |
| UPS overload | The connected equipment exceeds the rated power | Reduce load |
| Defective transformer T2 | Replace T2 | |
| Defective current sensor CT1 | Replace CT1. A resistance greater than 4 ohms indicates a faulty current sensor | |
| Defective IC15 | Replace IC15. Check the voltage -8 V and 5 V. Check and replace if necessary: IC12, IC8, IC17, IC14 and the power field-effect transistors of the inverter. Check power transformer windings | |
| Battery does not charge | UPS program is not working properly | Calibrate the battery voltage with a proprietary program from the APC. Check constants 4, 5, 6, 0. Constant 0 is critical for every UPS model. Check the constant after replacing the battery. |
| The battery charging circuit is out of order | Replace IC14. Check the 8 V voltage at the pin. 9 IC14, if not, then replace C88 or IC17 | |
| Battery defective | Replace battery. Its capacity can be checked with a high beam lamp from a car (12V, 150W) | |
| Microprocessor IC12 defective | Replace IC12 | |
| UPS does not start when turned on, click is heard | Defective reset circuit | Check serviceability and replace faulty elements: IC11, IC15, Q51 ... Q53, R115, C77 |
| Indicator defect | The indication circuit is faulty | Check and replace faulty Q57 ... Q60 on the indicator board |
| UPS does not work in On-line mode | Defective board elements | Replace Q56. Check the health of the elements: Q55, Q54, IC12. IC13 is defective or will have to be reprogrammed. The program can be taken from a working UPS |
| When transferring to battery operation, the UPS shuts down and turns on spontaneously | Broken transistor Q3 | Replace transistor Q3 |
In the second part of the article, the UPS device of the On-line class will be considered,
OFF-LINE UPS UNIT
APC Off-line UPS includes Back-UPS models. UPSs of this class are distinguished by their low cost and are designed to protect personal computers, workstations, network equipment, trade and point-of-sale terminals. Power of manufactured Back-UPS models is from 250 to 1250 VA. The main technical data of the most common UPS models are presented in table. 3.
Table 3. Main technical data of UPS class Back-UPS
| Model | BK250I | BK400I | BK600I |
|---|---|---|---|
| Rated input voltage, V | 220...240 | ||
| Rated mains frequency, Hz | 50 | ||
| Energy of absorbed emissions, J | 320 | ||
| Peak emission current, A | 6500 | ||
| IEEE 587 Cat. A 6kVA,% | <1 | ||
| Switching voltage, V | 166...196 | ||
| Output voltage when operating from batteries, V | 225 ± 5% | ||
| Output frequency when operating on batteries, Hz | 50 ± 3% | ||
| Maximum power, VA (W) | 250(170) | 400(250) | 600(400) |
| Power factor | 0,5. ..1,0 | ||
| Crest factor | <5 | ||
| Nominal switching time, ms | 5 | ||
| Number of batteries x voltage, V | 2x6 | 1x12 | 2x6 |
| Battery capacity, Ah | 4 | 7 | 10 |
| Time of 90-% recharging after discharging to 50%, hour | 6 | 7 | 10 |
| Acoustic noise at a distance of 91 cm from the device, dB | <40 | ||
| UPS operating time at full capacity, min | >5 | ||
| Maximum dimensions (H x W x D), mm | 168x119x361 | ||
| Weight, kg | 5,4 | 9,5 | 11,3 |
The index "I" (International) in the names of UPS models means that the models are designed for an input voltage of 230 V, the devices are equipped with sealed lead-acid maintenance-free batteries with a service life of 3 ... 5 years according to the Euro Bat standard. All models are equipped with suppressor filters that suppress surges and high-frequency noise in the mains voltage. The devices give appropriate sound signals when the input voltage is lost, the batteries are discharged and overloaded. The utility voltage threshold below which the UPS switches to battery operation is set using the switches on the rear of the unit. Models BK400I and BK600I have an interface port that can be connected to a computer or server for automatic self-closing of the system, a test switch and a beep switch.
The block diagram of the UPS Back-UPS 250I, 400I and 600I is shown in Fig. 8. Mains voltage is supplied to the input multistage filter through a circuit breaker. The circuit breaker is designed as a circuit breaker on the back of the UPS. In the event of a significant overload, it disconnects the device from the network, while the contact column of the switch is pushed up. To turn on the UPS after an overload, it is necessary to reset the contact bar of the breaker. The input EMI and RFI suppressor uses LC links and metal oxide varistors. During normal operation, pins 3 and 5 of RY1 are closed and the UPS transfers utility power to the load, filtering out high frequency interference. The charging current flows continuously as long as there is voltage in the network. If the input voltage drops below the set value or disappears altogether, or if it is very noisy, contacts 3 and 4 of the relay close, and the UPS switches to operation from the inverter, which converts the DC voltage of the batteries into AC. The switching time is about 5 ms, which is quite acceptable for modern switching power supplies for computers. The waveform at the load is rectangular pulses of positive and negative polarity with a frequency of 50 Hz, a duration of 5 ms, an amplitude of 300 V, an effective voltage of 225 V. At idle, the pulse duration is reduced and the effective output voltage drops to 208 V. Unlike Smart models -UPS, the Back-UPS does not have a microprocessor, comparators and logic chips are used to control the device.
A schematic diagram of the Back-UPS 250I, 400I and 600I is shown almost completely in Fig. 9 ... 11. The multi-tier power supply noise suppression filter consists of varistors MOV2, MOV5, chokes L1 and L2, capacitors C38 and C40 (Fig. 9). Transformer T1 (Fig. 10) is an input voltage sensor. Its output voltage is used to charge batteries (this circuit uses D4 ... D8, IC1, R9 ... R11, C3 and VR1) and to analyze the mains voltage.
If it disappears, then the circuit on the elements IC2 ... IC4 and IC7 connects a powerful inverter, powered by a battery. The ACFAIL command to turn on the inverter is generated by IC3 and IC4. The circuit, consisting of comparator IC4 (pins 6, 7, 1) and electronic key IC6 (pins 10, 11, 12), enables the operation of the inverter with a log signal. "1" going to pins 1 and 13 of IC2.
The divider, consisting of resistors R55, R122, R1 23 and switch SW1 (pins 2, 7 and 3, 6), located on the rear side of the UPS, determines the mains voltage below which the UPS switches to battery power. The factory setting for this voltage is 196 V. In areas with frequent fluctuations in the mains voltage resulting in frequent UPS switches to battery power, the threshold voltage should be set to a lower level. The fine adjustment of the threshold voltage is performed by the VR2 resistor.
During battery operation, IC7 generates inverter excitation pulses PUSHPL1 and PUSHPL2. In one arm of the inverter, powerful field-effect transistors Q4 ... Q6 and Q36 are installed, in the other -Q1 ... Q3 and Q37. The transistors are loaded onto the output transformer by their collectors. An impulse voltage with an effective value of 225 V and a frequency of 50 Hz is formed on the secondary winding of the output transformer, which is used to power the equipment connected to the UPS. The duration of the pulses is regulated by the variable resistor VR3, and the frequency - by the resistor VR4 (Fig. 10). Turning on and off the inverter is synchronized with the mains voltage by the circuit on the elements IC3 (pins 3 ... 6), IC6 (pins 3 ... 5, 6, 8, 9) and IC5 (pins 1 ... 3 and 11 ... thirteen). Circuit on the elements SW1 (pins 1 and 8), IC5 (pins 4 ... B and 8 ... 10), IC2 (pins 8 ... 10), IC3 (pins 1 and 2), IC10 (pins 12 and 13), D30, D31, D18, Q9, BZ1 (fig. 11) activates a buzzer to warn the user of a power problem. During battery operation, the UPS emits a single beep every 5 seconds to indicate the need to save user files. battery capacity is limited. When operating on battery power, the UPS monitors battery capacity and emits a continuous beep for a specified time before battery discharge. If pins 4 and 5 of switch SW1 are open, then this time is 2 minutes, if closed - 5 minutes. To turn off the sound signal, you must close the terminals 1 and 8 of the SW1 switch.
All Back-UPS models, with the exception of the BK250I, have a bi-directional communication port for communication with a PC. Power Chute Plus software allows the computer to both monitor the UPS and safely shutdown the operating system (Novell, Netware, Windows NT, IBM OS / 2, Lan Server, Scounix and UnixWare, Windows 95/98) while saving user files. In fig. 11 this port is designated J14. Purpose of its conclusions: 1 - UPS SHUTDOWN. The UPS shuts down if a log appears on this pin. "1" for 0.5 s.
2 - AC FAIL. When switching to battery power, the UPS generates a log on this output. "one".
3 - CC AC FAIL. When switching to battery power, the UPS generates a log on this output. "0". Open collector output.
4, 9 - DB-9 GROUND. Common wire for signal input / output. The terminal has a resistance of 20 ohms with respect to the common wire of the UPS.
5 - CC LOW BATTERY. In the event of a battery discharge, the UPS generates a log on this output. "0". Open collector output.
6 - OS AC FAIL When switching to battery power, the UPS generates a log on this output. "one". Open collector output.
7, 8 - not connected.
Open collector outputs can be connected to TTL circuits. Their load capacity is up to 50 mA, 40 V. If you need to connect a relay to them, then the winding should be shunted with a diode.
A regular "null modem" cable is not suitable for this port, the corresponding RS-232 interface cable with a 9-pin connector is supplied with the software.
UPS CALIBRATION AND REPAIR
Setting the frequency of the output voltage
To set the frequency of the output voltage, connect an oscilloscope or frequency meter to the UPS output. Turn the UPS into battery mode. When measuring the frequency at the UPS output, adjust the VR4 resistor to set 50 ± 0.6 Hz.
Setting the output voltage value
Turn the UPS into battery mode without load. Connect a voltmeter to the UPS output to measure the effective voltage value. By adjusting the VR3 resistor, set the voltage at the UPS output to 208 ± 2 V.
Setting the threshold voltage
Set switches 2 and 3 on the rear of the UPS to OFF. Connect the UPS to a LATR-type transformer with continuously variable output voltage. Set the voltage of 196 V at the LATR output. Turn the VR2 resistor counterclockwise until it stops, then slowly turn the VR2 resistor clockwise until the UPS switches to battery power.
Setting the charging voltage
Set the UPS input to 230 V. Disconnect the red wire to the positive battery terminal. Using a digital voltmeter, adjust the VR1 resistor to set the voltage on this wire to 13.76 ± 0.2 V relative to the common point of the circuit, then restore the connection to the battery.
Typical malfunctions
Typical malfunctions and methods for their elimination are given in table. 4, and in table. 5 - analogs of the most frequently failing components.
Table 4. Typical Back-UPS 250I, 400I and 600I Faults
| Defect manifestation | Possible reason | Defect finding and elimination method |
|---|---|---|
| Smoke smell, UPS is not working | Input filter defective | Check the health of the MOV2, MOV5, L1, L2, C38, C40 components, as well as the board conductors connecting them |
| UPS will not turn on. Indicator is off | UPS input circuit breaker (circuit breaker) disabled | Reduce the load on the UPS by turning off some of the equipment, and then turn on the circuit breaker by pressing the contact column of the circuit breaker |
| Defective accumulator batteries | Replace batteries | |
| Batteries not connected correctly | Check if the batteries are connected correctly | |
| Inverter defective | Check that the inverter is working properly. To do this, disconnect the UPS from the AC mains, disconnect the batteries and discharge the C3 capacity with a 100 Ohm resistor, ring the drain-source channels of the powerful field-effect transistors Q1 ... Q6, Q37, Q36 with an ohmmeter. If the resistance is a few ohms or less, replace the transistors. Check the resistors in the gates R1 ... R3, R6 ... R8, R147, R148. Check the health of transistors Q30, Q31 and diodes D36 ... D38 and D41. Check fuses F1 and F2 | |
| Replace IC2 | ||
| When turned on, the UPS disconnects the load | Defective transformer T1 | Check the health of the windings of the transformer T1. Check the tracks on the board connecting the T1 windings. Check fuse F3 |
| The UPS is operating on battery power even though mains voltage is present | The mains voltage is very low or distorted | Check the input voltage with an indicator or meter. If it is permissible for the load, reduce the sensitivity of the UPS, i.e. change the response limit using switches located on the back of the device |
| UPS turns on, but no voltage is supplied to the load | Defective relay RY1 | Check the health of relay RY1 and transistor Q10 (BUZ71). Check the health of IC4 and IC3 and the supply voltage at their terminals |
| Check the tracks on the board connecting the relay contacts | ||
| The UPS hums and / or shuts down the load, not providing the expected backup time | Defective inverter or one of its components | See sub-item "Inverter defective" |
| UPS does not provide expected backup time | Batteries are flat or lost capacity | Charge the batteries. They need to be recharged after extended power outages. In addition, batteries age quickly with frequent use or under high temperature conditions. If the batteries are nearing the end of their service life, it is advisable to replace them, even if the battery replacement alarm has not yet been sounded. Check the capacity of the charged battery with a car high beam 12 V, 150 W |
| UPS overloaded | Reduce the number of consumers at the UPS output | |
| UPS does not turn on after battery replacement | Incorrect battery connection when replacing | Check if the batteries are connected correctly |
| The UPS emits a loud tone when turning on, sometimes with a decreasing tone | Defective or discharged rechargeable batteries | Charge the batteries for at least four hours. If the problem persists after recharging, the batteries should be replaced. |
| Batteries do not charge | Diode D8 is faulty | Check if D8 is working properly. Its reverse current should not exceed 10 μA |
| Charge voltage below required level | Calibrate Battery Charge Voltage |
Table 5. Analogs for replacing defective components
| Schematic designation | Defective component | Possible replacement |
|---|---|---|
| IC1 | LM317T | LM117H, LM117K |
| IC2 | CD4001 | K561LE5 |
| IC3, IC10 | 74S14 | Consists of two K561TL1 microcircuits, the outputs of which are connected according to the pinout on the microcircuit |
| IC4 | LM339 | K1401SA1 |
| IC5 | CD4011 | K561LA7 |
| IC6 | CD4066 | K561KT3 |
| D4 ... D8, D47, D25 ... D28 | 1N4005 | 1N4006, 1N4007, BY126, BY127, BY133, BY134, 1N5618 ... 1N5622, 1N4937 |
| Q10 | BUZ71 | BUZ10, 2SK673, 2SK971, BUK442 ... BUK450, BUK543 ... BUK550 |
| Q22 | IRF743 | IRF742, MTP10N35, MTP10N40, 2SK554, 2SK555 |
| Q8, Q21, Q35, Q31, Q12, Q9, Q27, Q28, Q32, Q33 | PN2222 | 2N2222, BS540, BS541, BSW61 ... BSW 64, 2N4014 |
| Q11, Q29, Q25, Q26, Q24 | PN2907 | 2N2907, 2N4026 ... 2N4029 |
| Q1 ... Q6, Q36, Q37 | IRFZ42 | BUZ11, BUZ12, PRFZ42 |
Gennady Yablonin
"Repair of electronic equipment"
Uninterruptible Power Supply Failures
An uninterruptible power supply (Fig. 1.14) is a device that is highly desirable for creating normal conditions for a computer. Not only the stability of the computer depends on it, but also the frequency of occurrence of hardware faults.
Uninterruptible power supplies, sadly, can also fail. Although, as practice shows, the only thing that needs to be done to prevent damage to this device is to change the batteries in time.
As for the repair of an uninterruptible power supply at home, then, having a little understanding of the basics of electrical engineering and having a multimeter, you can independently determine and eliminate the causes of many malfunctions.
Rice. 1.14. Uninterruptible power system
Load connectors
If the indication of the uninterruptible power supply does not show any deviations in its operation, and there is no voltage at the outputs, then first of all it is necessary to check the output sockets on the back of the device.
Disassemble the uninterruptible power supply and remove the back panel from it. Pay attention to the wires coming from the AC input connector and regulators. To one output (usually marked white), the wires should go directly from the input, and to the outputs connected in parallel using plates, two wires from the stabilizers should go - red and yellow (Fig.1.15).
Rice. 1.15. Outlets on the back wall of the unit
If you see some kind of violation, such as a sealed wire or plate, arm yourself with a soldering iron and fix the problem. If all the wires are in place, then the cause of the malfunction should be looked for elsewhere.
Circuit breakers
Like any other AC-powered device, the UPS is fused. Fuses allow you to quickly disconnect the entire electronic control circuit in the event of a short circuit or other serious malfunction.
Usually, an uninterruptible power supply is equipped with a pair of fuses enclosed in a plastic sheath, that is, made in the form of a key that closes the circuit. They have different powers, and, as a rule, the fuse with weaker characteristics blows out.
After pulling each one out, make sure that the connecting thread between the fuse contacts is not broken. Otherwise, they must be replaced. For an easy search for a blown fuse, you can use a multimeter to check for resistance. If the fuse is good, the multimeter will show a resistance of several ohms, otherwise there will be no readings.
Transformer
The uninterruptible power supply contains a power transformer that is designed to step down or step up voltage by exploiting the magnetic properties of the transformer. Using a power transformer allows you to achieve higher output power than switching power supplies. On the other hand, it makes the device heavier.
Be that as it may, quite often a short circuit occurs in the transformer winding and the winding partially burns out. This can be facilitated by rather difficult conditions for using an uninterruptible power supply (instability of the input voltage, constant voltage surges and powerful impulse noise, for example, from a laser printer or copier, high humidity in the room, etc.). In this case, the transformer gets very hot, and its further use is possible only after the short circuit is eliminated.
If the transformer gets very hot, check all windings in pairs with a multimeter. If damage is found, the transformer must be replaced, since at home it is quite difficult to make a new winding with the desired characteristics.
High voltage transistors
As in any other electronic device, an uninterruptible power supply circuit must contain components that are subjected to serious loads, passing a high current through them. At the same time, heat generation increases, and if the cooling system does not cope with its functions, then these components simply burn out.
It is quite simple to make sure of this: take a close look at their appearance. As a rule, such components are cracked, and sometimes they are so destroyed that only their conclusions remain in their place.
As a rule, such elements are powerful transistors or microcircuits installed on aluminum radiators (Fig. 1.16). The minimum number of transistors is two. High-quality uninterruptible power supplies usually contain more than four transistors.
Rice. 1.16. Powerful field-effect transistors
To check the transistors, use a multimeter, having previously specified the location of the semiconductor junctions in the transistors in a special reference book or on the Internet, using the markings on the transistor case. As a rule, transistors fail in pairs, therefore, having found one faulty element, continue further testing.
Accumulator battery
The storage battery (Fig. 1.17) is one of the main components of an uninterruptible power supply. Depending on the capacity, an uninterruptible power supply can contain multiple batteries. The power of the unit and the battery life of the devices connected to it depend on the state of the battery and their capacity.
Rice. 1.17. Accumulator battery
Battery life is three to four years. However, in conditions of frequent power outages or when the power supply is operating in an overloaded mode, the battery life is halved and is usually less than two years.
Checking the battery status is easy enough. If the battery life of the computer is less than five minutes, the battery should be replaced. If the uninterruptible power supply turns off immediately after a power outage from the mains, then the battery must be replaced as soon as possible, otherwise it will let you down at the most inopportune moment.
The battery should also be replaced if you notice external swelling or strong oxidation of the terminals. In addition, the battery case may be cracked or electrolyte may leak.
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From the author's bookFaults and Remedies Imagine the situation. You come from university or work, from a friend, or returned home after a grueling shopping trip. We sat down at the computer, and oh, horror! He doesn't listen to you! No, he just ignores you and does not even react to
And, so your uninterruptible power supply sounded. What to do in this situation? Someone begins to hang himself, someone digs a grave. But, we will try to calm down and understand the reason for what is happening. Why is the UPS beeping? Probably because he is trying to draw your attention to himself. It is logical to assume that any electronic device that emits sound signals is trying to tell us that it "does not feel good". The main thing is to understand one thing, if the uninterruptible power supply beeps, it means that it is alive, but requires attention. And in how he squeaks, we are now and will try to figure it out.
To understand in more detail why the uninterruptible power supply beeps, let's take the APC Back-UPS CS 500 VA UPS for consideration.
And, as the instruction to the APC Back-UPS CS 500 VA uninterruptible power supply says, the UPS can beep in several cases, while it emits different sound signals:
- Four buzzer beeps every 30 seconds: This alarm sounds whenever the UPS switches to battery power. There is no reason for panic here. Just save all the documents you are currently working with and turn off your computer and UPS;
- Continuous Buzzer: This alarm sounds when the battery power is very low and the battery life is nearing the end. It is necessary to quickly save the documents and complete the work;
- A high tone beep for one minute every 5 hours: this alarm is given in case the battery fails the automatic check tests. In this case, it is necessary to replace the battery. You can replace the battery yourself, but we strongly recommend contacting the service center, since after replacing the battery in the uninterruptible power supply, the uninterruptible power supply itself needs to be calibrated. In some cases, in particular, it concerns double conversion UPS (SMART-UPS series), calibration is performed either through the control console or using specialized software.
- Continuous tone constant tone: This alarm is generated in case the UPS is overloaded. It is important to remember that any UPS, like power supplies, has a very important parameter called the maximum load power. In a nutshell, this is the maximum (total) power of devices that can be connected to the UPS outputs. If your uninterruptible power supply emits a continuous tone, it means that you need to disconnect any devices from it.
!! WHEN OPERATING UNINTERRUPTED POWER SUPPLIES IT IS IMPORTANT TO REMEMBER !!
1. The useful life of rechargeable batteries in an uninterruptible power supply is 2-3 years. Of course, this parameter is valid if the UPS was used in normal conditions and the average ambient temperature is 20-23 degrees Celsius. Any rechargeable batteries are very afraid of high (above 30 degrees Celsius) temperatures. Therefore, even if the uninterruptible power supply does not beep, and more than 2-3 years have passed since the start of operation, the battery in the uninterruptible power supply must be replaced.
2. In addition to sound signals, uninterruptible power supplies also provide visual signals. This will be discussed a little later. I will tell you what these visual cues mean. Visual cues may vary from manufacturer to manufacturer of uninterruptible power supplies, but not significantly.
3. An uninterruptible power supply, like any device, over time becomes overgrown with dust and dirt, which ultimately greatly affects the health of the battery, and the health of the uninterruptible power supply itself. Therefore, at least once every 1-1.5 years, do not be too lazy to take the UPS to the service center for preventive maintenance. This will save your nerves in the future and increase the service life of the uninterruptible power supply;
4. If a bad battery is installed in the uninterruptible power supply, then there are situations when it can beep, beep and give out visual signals, as well as there are cases when your uninterruptible power supply will not turn on;
APC Back-UPS CS 500VA VISUAL SIGNALS
And so, the picture above shows the front panel of the APC Back-UPS CS 500 VA uninterruptible power supply. Let's take a look at what all these bulbs mean.
Green indicator. This indicator is on in all cases when external voltage is supplied to the uninterruptible power supply;
The indicator is yellow. This indicator lights up when the external power supply to the uninterruptible power supply is cut off and it switches to battery power;
Red indicator. This indicator comes on when the power consumption of devices connected to the outlets of the uninterruptible power supply exceeds the maximum allowable power of the UPS itself.
Red indicator. This indicator comes on when the battery is about to expire or the battery is not connected to an uninterruptible power supply. A battery that has expired or has already expired does not provide sufficient battery life for the UPS and must be replaced;
First of all, let's pay attention to the fact that this uninterruptible power supply has an LCD display that displays the status of the UPS in real time. According to the instructions for the IPPON Back Power Pro LCD Euro uninterruptible power supply, the values on the LCD display can be as follows:
Having figured out what kind of indication can be on the display of the IPPON Back Power Pro LCD Euro UPS, let's move on to explaining the different types of indication and sound signals.
Indication on the LCD display of the IPPON Back Power Pro LCD Euro UPS and sound signals for various operating modes
At the same time, let's take a look at the varieties of the battery charge indicator of the IPPON Back Power Pro LCD Euro UPS and the sound signals that the uninterruptible power supply can emit at different battery charge levels.
UPS IPPON Back Power Pro LCD Euro signals visually and by means of a sound signal not only in cases of breakdown or battery discharge, but also in cases of overload
And so, we looked at the visual and audible signals of the APC and IPPON UPS. In the following, the article will be supplemented with documentation and descriptions of signals from uninterruptible power supplies and other manufacturers.
The specialists of our company are ready to advise you on any issue related to the use, maintenance, and repair of uninterruptible power supplies. You can find prices for repairing uninterruptible power supplies, replacing batteries in uninterruptible power supplies in the corresponding section.
